In the past, various different devices and methods have been proposed for treating liquids with electromagnetic flux for the purpose of reducing the scaling propensity of the liquid, for reducing the number of living microorganisms contained in the liquid or for other purposes. For example, an apparatus for treating flowing liquid with electromagnetic flux is disclosed in U.S. Pat. No. 6,063,267 assigned to Clearwater Systems, LLC, the disclosure of which is herein incorporated by reference.
Some of these prior devices have used either stationary or movable permanent magnets for producing a magnetic flux. Other devices have used electrical coils arranged in various different ways with respect to pipes conducting the liquid. These devices create an electromagnetic flux used as the liquid treatment factor by energizing the coils with either a direct or alternating source. In the case of devices using electromagnetic flux, it is known from U.S. Pat. No. 5,702,600 to provide an apparatus including a plurality of electrical coils surrounding different separate longitudinal sections of a liquid conducting pipe, with two of the coils being wound on top of one another, a diode being so connected in circuit with the coils and with the power source that current from the power source is conducted through the coils only during alternate half-cycles of one voltage polarity, with some current of a ringing nature apparently flowing through each coil following the end of each half-cycle of diode conduction. Devices of this type produce two types of electromagnetic fields. During the portion of the AC power cycle in which the diode conducts, the coils produce a low frequency (commonly 50 or 60 Hz) electromagnetic field. The generation of this field requires that substantial current flow through the diode and the coils. During the portion of the AC power cycle in which the diode does not conduct, the coils, in conjunction with stray or discrete capacitance in the circuit, generates a high frequency ringing electromagnetic field. Both types of electromagnetic fields generated are thought to be significant in the treatment of flowing liquids. However, the ringing current, and the electromagnetic flux produced by devices such as that described in the '600 patent appear to be weak and of very short duration so as to be of small effectiveness.
Prior systems for treating flowing liquids with a ringing magnetic pulse used a diode switch to interrupt the coil current when the current reversed polarity. For example, a prior analog control system produced a relatively small “ringing” pulse on the coil voltage when the current was blocked by the diode because there was still voltage remaining on the coil capacitance. The analog control system was modified to generate a much larger “ringing” voltage of up to ten times that of the above-mentioned previous analog control system. This design used in place of the diode, a switch comprising up to ten parallel-connected 450 volt MOSFETs. This switch interrupted the current flow before the coil current reached zero, leaving stored magnetic energy in the coil which powered the larger “ringing” pulse. With this approach, a switch is needed that can be electronically “turned off”, and such switches tend to be low current devices with relatively high “ON state” resistance. As a result, ten switches in parallel are needed to handle the full coil current.
Digital control systems have been developed in order to improve stability of operation relative to that of the above-mentioned prior analog control systems. However, there is still a need to lower the complexity and cost of such digital control systems. Irrespective of whether digital or analog control is used, devices of this type produce ringing pulses which are believed to provide better fluid treatment, however, the circuitry required to produce both the low frequency and ringing electromagnetic fields in these devices is sufficiently complex and inefficient so as to be considered less than desirable.
Accordingly, it is a general object of the present invention to provide an apparatus and method of treating liquid with a ringing magnetic pulse which overcomes the above-mentioned drawbacks and disadvantages in generating both low and high frequency electromagnetic fields associated with prior systems and methods of treating liquids.